feat(page): add an option to disable timeout for waitForFunction

docs/api.md

@@ -1344,7 +1344,7 @@ Shortcut for [page.mainFrame().waitFor(selectorOrFunctionOrTimeout[, options[, .
   - `polling` <[string]|[number]> An interval at which the `pageFunction` is executed, defaults to `raf`. If `polling` is a number, then it is treated as an interval in milliseconds at which the function would be executed. If `polling` is a string, then it can be one of the following values:
     - `raf` - to constantly execute `pageFunction` in `requestAnimationFrame` callback. This is the tightest polling mode which is suitable to observe styling changes.
     - `mutation` - to execute `pageFunction` on every DOM mutation.
-  - `timeout` <[number]> maximum time to wait for in milliseconds. Defaults to `30000` (30 seconds).
+  - `timeout` <[number]> maximum time to wait for in milliseconds. Defaults to `30000` (30 seconds). Pass `0` to disable timeout.
 - `...args` <...[Serializable]|[JSHandle]> Arguments to pass to  `pageFunction`
 - returns: <[Promise]<[JSHandle]>> Promise which resolves when the `pageFunction` returns a truthy value. It resolves to a JSHandle of the truthy value.
 
@@ -1377,7 +1377,7 @@ Shortcut for [page.mainFrame().waitForFunction(pageFunction[, options[, ...args]
 - `options` <[Object]> Optional waiting parameters
   - `visible` <[boolean]> wait for element to be present in DOM and to be visible, i.e. to not have `display: none` or `visibility: hidden` CSS properties. Defaults to `false`.
   - `hidden` <[boolean]> wait for element to not be found in the DOM or to be hidden, i.e. have `display: none` or `visibility: hidden` CSS properties. Defaults to `false`.
-  - `timeout` <[number]> maximum time to wait for in milliseconds. Defaults to `30000` (30 seconds).
+  - `timeout` <[number]> maximum time to wait for in milliseconds. Defaults to `30000` (30 seconds). Pass `0` to disable timeout.
 - returns: <[Promise]<[ElementHandle]>> Promise which resolves when element specified by selector string is added to DOM.
 
 Wait for the `selector` to appear in page. If at the moment of calling
@@ -1406,7 +1406,7 @@ Shortcut for [page.mainFrame().waitForSelector(selector[, options])](#framewaitf
 - `options` <[Object]> Optional waiting parameters
   - `visible` <[boolean]> wait for element to be present in DOM and to be visible, i.e. to not have `display: none` or `visibility: hidden` CSS properties. Defaults to `false`.
   - `hidden` <[boolean]> wait for element to not be found in the DOM or to be hidden, i.e. have `display: none` or `visibility: hidden` CSS properties. Defaults to `false`.
-  - `timeout` <[number]> maximum time to wait for in milliseconds. Defaults to `30000` (30 seconds).
+  - `timeout` <[number]> maximum time to wait for in milliseconds. Defaults to `30000` (30 seconds). Pass `0` to disable timeout.
 - returns: <[Promise]<[ElementHandle]>> Promise which resolves when element specified by xpath string is added to DOM.
 
 Wait for the `xpath` to appear in page. If at the moment of calling
@@ -1926,7 +1926,7 @@ This method behaves differently with respect to the type of the first parameter:
   - `polling` <[string]|[number]> An interval at which the `pageFunction` is executed, defaults to `raf`. If `polling` is a number, then it is treated as an interval in milliseconds at which the function would be executed. If `polling` is a string, then it can be one of the following values:
     - `raf` - to constantly execute `pageFunction` in `requestAnimationFrame` callback. This is the tightest polling mode which is suitable to observe styling changes.
     - `mutation` - to execute `pageFunction` on every DOM mutation.
-  - `timeout` <[number]> maximum time to wait for in milliseconds. Defaults to `30000` (30 seconds).
+  - `timeout` <[number]> maximum time to wait for in milliseconds. Defaults to `30000` (30 seconds). Pass `0` to disable timeout.
 - `...args` <...[Serializable]|[JSHandle]> Arguments to pass to  `pageFunction`
 - returns: <[Promise]<[JSHandle]>> Promise which resolves when the `pageFunction` returns a truthy value. It resolves to a JSHandle of the truthy value.
 

lib/FrameManager.js

@@ -790,7 +790,8 @@ class WaitTask {
     });
     // Since page navigation requires us to re-install the pageScript, we should track
     // timeout on our end.
-    this._timeoutTimer = setTimeout(() => this.terminate(new Error(`waiting failed: timeout ${timeout}ms exceeded`)), timeout);
+    if (timeout)
+      this._timeoutTimer = setTimeout(() => this.terminate(new Error(`waiting failed: timeout ${timeout}ms exceeded`)), timeout);
     this.rerun();
   }
 

test/frame.spec.js

@@ -145,6 +145,12 @@ module.exports.addTests = function({testRunner, expect}) {
       await page.evaluate(element => element.remove(), div);
       await waitForFunction;
     });
+    it('should disable timeout when its set to 0', async({page}) => {
+      let error = null;
+      const res = await page.waitForFunction(() => new Promise(res => setTimeout(() => res(42), 100)), {timeout: 0}).catch(e => error = e);
+      expect(error).toBe(null);
+      expect(await res.jsonValue()).toBe(42);
+    });
   });
 
   describe('Frame.waitForSelector', function() {